Orthodontic procedures typically involve repositioning a patient's teeth to a desired arrangement in order to correct malocclusions and/or improve aesthetics. To achieve these objectives, orthodontic appliances such as braces, retainers, shell aligners, and the like can be applied to the patient's teeth by an orthodontic practitioner and/or a patient. The appliance is configured to exert force on one or more teeth in order to effect desired tooth movements. The application of force can be periodically adjusted (e.g., by altering the appliance or using different types of appliances) in order to incrementally reposition the teeth to a desired arrangement.
It may be desirable to provide designs and/or written information on the surface of the aligner. Many aligner surfaces, however, present challenges with respect to reliable printing. In particular, ink adhesion can be challenging in view of the low surface energy material that forms many aligners, including plastics and polymers. In addition, the oral environment in which many aligner are used may be wet, may have high humidity, high temperature, and/or saliva containing various enzymes and other components designed to break-down materials. An oral environment may also cause mechanical rubbing against an aligner therein, making reliable and safe ink printing on the aligner surface challenging, particularly for an extended duration of time. Additionally, labels affixed to the surface of an aligner, particularly one in an oral environment, may present challenges. Although etching is useful in some contexts, such as those described in U.S. Pat. Pub. No. 2017/000833 filed Jul. 5, 2016 titled “Dental Appliance Having Ornamental Design,” etching may not be useful in some contexts.